It is already known that the racemate of 2-[2-(1-chloro-cyclopropyl)-3-(2-chlorophenyl)-2-hydroxypropyl]-2,4-dihydro-[1,2,4]-triazole-3-thione has fungicidal properties (cf. WO 96-16 048). The activity of this substance is good; however, at very low application rates it is sometimes unsatisfactory.
This invention, accordingly, provides the novel (−)-enantiomer of 2-[2-(1-chloro-cyclopropyl)-3-(2-chlorophenyl)-2-hydroxypropyl]-2,4-dihydro-[1,2,4]-triazole-3-thione of the formula

Here, the (−)-enantiomer is in each case to be understood as the enantiomer which rotates the plane of vibration of linear-polarized light of the sodium D-line to the left.
Furthermore, it has been found that the (−)-enantiomer of 2-[2-(1-chloro-cyclopropyl)-3-(2-chloro-phenyl)-2-hydroxypropyl]-2,4-dihydro-[1,2,4]-triazole-3-thione of the formula (I) is obtained when    a) racemic 2-[2-(1-chloro-cyclopropyl)-3-(2-chloro-phenyl)-2-hydroxypropyl]-2,4-dihydro-[1,2,4]-triazole-3-thione of the formula
     is chromatographed on a chiral stationary silica gel phase based on the optically active monomer N-methacryloyl-L-leucine-3-(2,4-dimethylpentyl)-amide using ethyl acetate as mobile phase at temperatures between 20° C. and 25° C.,    b) the eluate is concentrated under reduced pressure and    c) the resulting product is recrystallized from toluene.